1. Field of the Invention
The field of the invention is interface apparatus coupled between a minicomputer and a microcomputer, for facilitating the transfer of data between the computers.
2. Description of the Prior Art
Heretofore various apparatus have been proposed and utilized for interfacing between computers and more specifically between minicomputers and microcomputers. One commonly used device is known by the Ser. No. RS232 and is an asynchronous interface device which provides for serial transfer of data between one computer and another computer. The asynchronous device can operate over virtually unlimited distances but is usually limited to a transfer rate of 9600 bits/second or less. Thus, although the RS232 can operate over unlimited distances, the transfer rate is rather slow. Such an interface device is described in a technical report dated August, 1969 issued by the Electronic Industries Association under the Ser. No. RS-232-C.
In applications where higher data transfer rates are required, a parallel interface apparatus can be utilized such as the so-called "INTEL.sub.TM Multibus", provided long distances are not involved.
According to the teachings of the present invention and as will be described in greater detail hereinafter, the interface apparatus of the present invention is usable for distances of up to at least 200 feet (61 meters) long conductors as opposed to short conductors of 1 ft (30 cm) or less while at the same time providing a transfer rate by means of parallel data lines which is essentially limited only by the speed of the direct memory access controller in the minicomputer and the speed of operation of the microcomputer. With the parallel data line interface apparatus of the present invention a transfer rate of 100,000 words per second, the equivalent of 1.6 megabits per second, is easily attained.